Lower leaves turning yellow on young plant

This is my latest girl - a Banana Blaze. She's 4 weeks into veg, growing in soil (fox farm ocean forest). So far no nutes and been watered with nothing but distilled water until about 3 days ago. Started with 24/0 and switched to 18/6 about a week ago. I'd say size wise she's about a week behind my last few girls but that could just be the strain. So far I've done everything exactly the same way I've always done. Same soil, same schedule etc. Last few days I noticed the lowest leaves turn yellow. Everything above that is all nice and green. As you can see in the photo the very first leaves on the very bottom are yellow as well. So it's like the yellow is climbing.
Any ideas what could be going on?

Looks like nutrient deficiency. Start giving some nutes. If using distilled water, must supplement CalMag.

Are you letting the soil dry out between waterings? Don't keep it wet in the root zone all the time. Saturate at watering, then wait til the pot gets light before watering again.

“Feed me”

Definitely needs food..

Its time to take your girl to dinner, she's ate all the food in the pantry and she's hungry

UPDATE: Thank you, everyone for your replies! After reading your answers I immediately went and gave her some nutes. Upon closer inspection I noticed that none of her growth tips had grown either - they were all just a few millimeters when in previous grows they were at least a couple of inches at that point. So now a few days later I'm happy to say that while she lost the fan leaves that had gotten yellow no additional leaves have turned yellow. And it seems the growth tips are finally growing as well. I hope I caught this early enough in veg that it has not messed her up completely. I expect she'll be in veg a few weeks longer than usual to make up for it but that's ok. Anyway, thank you very much everyone, I appreciate your help!